The following account of the prior art relates to one of the areas of application of the present application, hearing aids.
Wireless links between mobile devices is of increasing importance. In connection with hearing aids, inductive links based on utilizing near-field properties of the electromagnetic field (inductive coupling between inductor coils in respective devices) communication have been widely used due to their relatively low power consumption (and appropriate, short range). The huge penetration of mobile telephones comprising wireless link capabilities based on far-field properties of the electromagnetic field (radiated fields, RF) and complying with the Bluetooth standard has influenced the field of hearing aids as well. Increasingly, wireless links involving hearing aids or accessories for hearing aids are based on Bluetooth or other proprietary or standardized, relatively low power (and correspondingly short range, e.g. less than 100 m) technologies (e.g. Bluetooth Low Energy, DECT, Wi-Fi (IEEE 802.11), ZigBee, etc.). In some cases, wireless links based on radiated fields and Bluetooth (operating in a non-licensed frequency range, e.g. ISM (ISM=Industrial, Scientific and Medical), e.g. around 865 MHz or 2.4 GHz) have replaced or taken the place of the inductive links.
When transmitting data on an RF carrier (e.g. in the GHz range) in a complex environment, the signal at the receiver will be impacted by two fading effects:                attenuation due to lossy materials (e.g. a body).        negative interference due to multipath effects (reflections from walls, etc., multi-path fading).        
As the device comprising the RF-receiver moves around in the complex environment relative to the RF-transmitter, the severity of the fading may change dramatically.
An RF-transmission comprising audio to a hearing aid from an audio delivery device (e.g. an audio gateway, a cellphone, a TV, a microphone, or other accessory) will be subject to the above challenges. Hence, reception from transmitting devices that are not provided with advanced means for compensating such variable fading effects (such as diversity antennas) will be challenging. In such cases, the problems must be solved at the receiving end, e.g. in a hearing aid.
US2008159548A1 describes wireless stereo reception of first and second audio information by wireless hearing communication devices, e.g. hearing assistance devices, such as hearing aids. Various forms and protocols of signal transmission are employed in varying embodiments, including various communication modes such as eavesdropping modes and relaying modes.
US2007291970A1 deals with wireless communication between hearing units of small construction, especially between hearing aids with an increased data rate. A hearing unit is fitted with a transceiver which has an inductive receiving device and a digital wideband pulse transmitter. Two such hearing units can then communicate wirelessly with one another with the help of a communication station which is structurally separate from the hearing units and with which a message can be transmitted from the one to the other of the hearing units. The digital wideband pulse transmitter can be implemented in a structurally small manner in the hearing unit and with low power consumption.